1. Field of the Invention
The present invention relates to a sheet process apparatus, and more particularly, it relates to a sheet process apparatus in which, after imaged sheets discharged from an image forming apparatus such as a copying machine, a printer and the like are aligned or stapled, the sheets are stably discharged onto a stacking means.
2. Related Background Art
There has been proposed a sheet process apparatus in which, sheets discharged on a process tray (first stacking means) are aligned or stapled, the sheets are discharged onto a stack tray (second stacking means). In such a process apparatus, in case of a non-stapled sheet bundle in which a sheet bundle discharged on the stack tray is not stapled by a stapler, if the number of sheets in the sheet bundle is too great, upper several sheets in a sheet bundle already stacked on the stack tray may be disordered to worsen the stacking ability. Thus, to avoid this, in the past, the number of the sheets in the bundle has been selected to be relatively small.
However, in the conventional sheet process apparatus, the number of non-stapled sheets discharged from the process tray was the same or constant (for example, several sheets) regardless of the size of the sheet. Thus, when a length of the sheet in a sheet conveying direction is small, the sheets can stably be discharged onto the stacking means; however, when a length of the sheet in the sheet conveying direction is great, the weight of the sheet bundle may push out the sheet bundle already stacked on the stacking means to worsen the stacking ability.